Power transformers are used to convert an alternating current power supply of the type available in homes, offices, hotels, and the like via an ordinary wall outlet to a direct current power supply compatible with electronic devices, such as radios-telephones, telephones, answering machines, calculators, computers, radios, and the like. These power transformers are used to reduce the dependence upon batteries or to provide charging energy for rechargeable batteries from available alternating current power supplies. To provide the regulated power supply, the transformer includes a power converting circuit within the housing having a male connector positioned thereon. The male connector is for a connection to a female connector of a main power supply wall outlet.
Because power transformers are often used with portable devices, they have been developed to facilitate transport with the portable devices. One known transformer includes pivoting prongs that move into the transformer housing for storage during travel, and pivot to an outwardly projecting position for connection to a wall outlet. These connectors have improved the compactness when folded to minimize the storage space which they require, thereby facilitating packing by travelers or commuters.
A difficulty encountered by international travelers is powering their electronic equipment. This difficulty arises because the power supplies in different countries have different voltages, currents, and supply frequency characteristics. They also have different wall outlet female connector configurations. Although power converter circuits have been developed which produce a regulated direct current voltage (e.g. 5 volts) from most main power supply signals found throughout the world, accommodating the different female connectors has been more difficult.